1 /* $OpenBSD: michael.c,v 1.2 2008/07/21 19:52:45 damien Exp $ */
2
3 /*
4 * Copyright (c) 2005, 2006 Reyk Floeter <reyk@openbsd.org>
5 *
6 * Permission to use, copy, modify, and distribute this software for any
7 * purpose with or without fee is hereby granted, provided that the above
8 * copyright notice and this permission notice appear in all copies.
9 *
10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17 */
18
19 /*
20 * Implementation of the Michael MIC as defined in IEEE 802.11i for TKIP.
21 * The MIC generates a 64bit digest, which shouldn't be used for any other
22 * applications except TKIP.
23 */
24
25 #include <sys/param.h>
26 #include <sys/systm.h>
27
28 #include <crypto/michael.h>
29
30 #define ROL(n, x) (((x) << (n)) | ((x) >> (32 - (n))))
31 #define ROR(n, x) (((x) >> (n)) | ((x) << (32 - (n))))
32 #define XSWAP(x) (((x) & 0xff00ff00UL) >> 8 | ((x) & 0x00ff00ffUL) << 8)
33
34 #if defined(__STRICT_ALIGNMENT) || _BYTE_ORDER != _LITTLE_ENDIAN
35 #define GETLE32(x) ((x)[0] | (x)[1] << 8 | (x)[2] << 16 | (x)[3] << 24)
36 #define PUTLE32(x, v) ((x)[0] = (u_int8_t)(v), \
37 (x)[1] = (u_int8_t)((v) >> 8), \
38 (x)[2] = (u_int8_t)((v) >> 16), \
39 (x)[3] = (u_int8_t)((v) >> 24))
40 #else
41 #define GETLE32(x) (*((u_int32_t *)(x)))
42 #define PUTLE32(x, v) (*((u_int32_t *)(x)) = (v))
43 #endif
44
45 #define MICHAEL_BLOCK(l, r) do { \
46 r ^= ROL(17, l); \
47 l += r; \
48 r ^= XSWAP(l); \
49 l += r; \
50 r ^= ROL(3, l); \
51 l += r; \
52 r ^= ROR(2, l); \
53 l += r; \
54 } while (0)
55
56 void
michael_init(MICHAEL_CTX * ctx)57 michael_init(MICHAEL_CTX *ctx)
58 {
59 bzero(ctx, sizeof(MICHAEL_CTX));
60 }
61
62 void
michael_update(MICHAEL_CTX * ctx,const u_int8_t * data,u_int len)63 michael_update(MICHAEL_CTX *ctx, const u_int8_t *data, u_int len)
64 {
65 int i;
66
67 for (i = 0; i < len; i++) {
68 ctx->michael_state |= data[i] << (ctx->michael_count << 3);
69 ctx->michael_count++;
70
71 if (ctx->michael_count >= MICHAEL_RAW_BLOCK_LENGTH) {
72 ctx->michael_l ^= ctx->michael_state;
73 MICHAEL_BLOCK(ctx->michael_l, ctx->michael_r);
74 ctx->michael_state = ctx->michael_count = 0;
75 }
76 }
77 }
78
79 void
michael_final(u_int8_t digest[MICHAEL_DIGEST_LENGTH],MICHAEL_CTX * ctx)80 michael_final(u_int8_t digest[MICHAEL_DIGEST_LENGTH], MICHAEL_CTX *ctx)
81 {
82 static const u_int8_t pad[] =
83 { 0x5a, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
84
85 michael_update(ctx, pad, sizeof(pad));
86
87 PUTLE32(digest, ctx->michael_l);
88 PUTLE32(digest + MICHAEL_RAW_BLOCK_LENGTH, ctx->michael_r);
89 }
90
91 void
michael_key(const u_int8_t * key,MICHAEL_CTX * ctx)92 michael_key(const u_int8_t *key, MICHAEL_CTX *ctx)
93 {
94 ctx->michael_l = ctx->michael_key[0] =
95 GETLE32(key);
96 ctx->michael_r = ctx->michael_key[1] =
97 GETLE32(key + MICHAEL_RAW_BLOCK_LENGTH);
98 }
99